Objective
To develop a protocol for cryopreservation and recovery of human endometrial epithelial cells (eEC) retaining molecular and functional characteristics of endometrial epithelium in vivo.
Design
This is an in vitro study using human endometrial cells.
Setting
University research laboratory.
Patients
Endometrial biopsies were obtained from premenopausal women undergoing benign gynecological procedures.
Interventions
Primary eEC were cryopreserved in 1% fetal bovine serum (FBS)/10% dimethyl sulfoxide (DMSO) in Defined Keratinocyte Serum Free Medium (KSFM). Recovered cells were observed for endometrial stromal fibroblast (eSF) contamination and subsequently evaluated for morphology, gene expression, and functional characteristics of freshly cultured eECs and in vivo endometrial epithelium.
Main Outcome Measures
Analysis of eEC morphology and the absence of eSF contamination; evaluation of epithelial-specific gene and protein expression; assessment of epithelial polarity.
Results
eEC recovered after cryopreservation (n=5) displayed epithelial morphology and expressed E-cadherin (CDH1), occludin (OCLN), claudin1 (CLDN1), and keratin18 (KRT18). Compared to eSF, recovered eEC displayed increased (P<0.05) expression of epithelial-specific genes AREG, CDH1, DEFB4A, MMP7, and WNT7A, while exhibiting low-to-undetectable (P<0.05) stromal-specific genes COL6A3, HOXA11, MMP2, PDGFRB, and WNT5A. Recovered eEC secrete levels of cytokines and growth factors comparable to freshly cultured eEC. Recovered eEC can formed a polarized monolayer with high transepithelial electrical resistance (TER) and impermeability to small molecules, and expressed apical/basolateral localization of CDH1 and apical localization of OCLN.
Conclusion
We have developed a protocol for cryopreservation of eEC in which recovered cells after thawing demonstrate morphological, transcriptomic, and functional characteristics of human endometrial epithelium in vivo.